Children with congenital hypothyroidism have persistently elevated thyrotropin (TSH) levels despite normal or high normal thyroxine levels. The use of resting energy expenditure (REE), as a measurement if basal metabolic activity, will be correlated with thyroid function tests. The hypothesis to be tested is that REE will correlate with thyroxine levels and not TSH. If this correlation is found, one possible interpretation is that the pituitary thyroxine receptor is up regulated during fetal development in a hypothyroid.